For a game under dev, with Chrome, it will play a background tune and then, while the background tune is playing, a second tune is played when an action is engaged.

IE9 doesn't do this...any ideas how to code to have a background tune continue playing while a second tune is tied to an action and doesn't cancel out the first tune?

Hello bigbasin,
The problem might be related with the audio file formats you are trying to play on Internet Explorer 9.

I've been working on playing audio on web pages using HTML5 for a while.
I experienced that you can play a number of sound files at the same time using Javascript and HTML5 audio element.
You can create dynamic audio objects on the fly and play sound with Javascript audio object Play() method.

Please check HTM5 tutorial showing how to play audio on HTML5

But if you do not hear the sound you expect to hear on Internet Explorer 9 (IE9), the cause of the problem is probably because Internet Explorer web browser does not support that audio file format on HTML5

You can convert sound file format or use an other sound file that Internet Explorer 9 web browser support